William wilhelm



(No Model.)

W. L. WILHELM. TELEPHONE TRANSMITTER.

No. 557,741. Patented Apr. 7, 1896.

WITN ESSES! INVENTOR.

ATTORNEYS.

AN DREW BJSRAHAM. PHOTO Lm o. WASHINGTON. BL

UNITED STATES IVALTER L. IVILHELM, OF BUFFALO, NEW YORK; WILLIAMIVILHELM PATENT OFFICE.

GUARDIAN OF SAID YVALTEB L. W'ILHELM, ASSIGNOR OF ONE-HALF TO BYRON J.TILLMAN, OF SAME PLACE.

TELEPHONE-TRANSMETTER.

SPECIFICATION forming part of Letters Patent No. 557,741, dated April*7, 1896.

Application filed November 21, 1895. Serial No. 569,621. (No model.)

To all whom, it may concern.-

Be it known that I, 'WALTER L. WILHELM, a citizen of the United States,residing at Buffalo, in the county of Erie and State of New York, haveinvented a new and useful Improvement in Telephone Transmitters, of

which the following is a specification.

This invention relates to that class of tele' phone microphones ortransmitters which con tain two separate diaphragms bearing againstopposite sides of the same electrode and a single mouthpiece from which.the sound is delivered by two branch tubes against both diaphragms.

The object of my invention is to produce a transmitter of this characterwhich is extremely simple and inexpensive in construc tion and which canbe easily assembled and adjusted.

In the accompanying drawings, Figure l is a sectional elevation of myimproved transmitter, taken in line 1 1, Fig. 2. Fig. 2 is a horizontalsection of the same in line 2 2, Fig. 1. Fig. 3 is a detached sideelevation of the transmitting device. Fig. at is a horizontal sectionshowing a modification of my improved transmitter.

Like letters of reference refer to like parts in the several figures.

Referring to Figs. 1, 2, and 3, A represents a mouthpiece, and a a twobranch tubes or passages connected at their front ends with the rear endof the mouthpiece.

B B represent two vertical supporting-disks secured to the open rearends of the branch tubes and arranged parallel. The supporting-disks areseparated from each other along their entire opposing surfaces, therebyforming an open-sided chamber or space between the supporting-disks,into which the transmitting devices can be inserted from the side forassembling the parts or to be removed therefrom for adjusting orrepairing the same. This transmitting device is constructed as follows:

0 represents a rotary supporting ring or frame, which is held snuglybetween the supportingdisks by friction, and which is provided onopposite sides with annular shoulders or seats 0 c.

D D represent two diaphragms, which are separated from thesupporting-disks by intervening spaces, and which are fitted with theirmarginal portions against the seats of the frame. These diaphragms maybe made of any suitable and well-known material which will answer thepurpose; but I prefer to make the same out of sheet-carbon.

E represents the electrode arranged between the diaphragms and bearingagainst the central portions of both diaphragms. This electrodeconsists, preferably, of a granular material, such as powdered carbon orcarbon dust, although some other granular substance might work equallyas well. granular electrode is confined in the central portion of thespace between the diaphragms by a retaining-ring F, which fills thespace between the electrode and the supportingframe. This retainingringis composed of any suitable fibrous material which is sufficiently denseto prevent the powdered carbon from being displaced by creepingbetweenthe fibers thereof, and which is sufiiciently elastic or yielding topermit the diaphragms to vibrate freely for infiu encing the electrode.I have found in practice that cotton, mineral wool, and eiderdown giveexcellent results.

G represents packing-rings arranged between the supporting-disks and themarginal portions of the diaphragms, whereby the latter are held inplace. The space between the supportingdisks is such that thetransmitting device will be securely held in position by friction afterit is slipped between the supporting-disks. The vertical arrangement ofthe diaphragms causes the carbon-dust electrode to be held in contactwith both diaphragms by gravity, thereby always insuring a good contactbetween these parts without requiring any special adjusting device forthis purpose.

When the carbon dust becomes packed or condensed in course of time bythe vibrations of the diaphragms, the carbon dust can be again loosenedfor restoring it to its normal condition by rotating the transmittingdevice between the supporting-disks sufiiciently to agitate and loosenthe carbon dust, thereby preventing the action of the transmitter frombecoming impaired.

H H represent two contact-springs which The form the terminals of theconducting-wires h h, and which are adapted to make connection with thecarbon diaphragms when the transmitting device is in its operativeposition. Each of these contactsprings is secured with one end to thebottom of a pocket h, formed on the inner side of a supporting disk andbearing with its curved free end against the adjacent diaphragm, therebyforming a circuit from one wire to the other through the diaphragms andthe electrode. Upon removing the transmitting device from between thedisks the springs slip off from the diaphragms and recede into thepockets upon striking the packing-ring and frame, whereby the circuit isbroken, and upon introducing the same again between the disks thesprings again bear on the diaphragms and automatically restore thecircuit, thereby enabling the working parts of the transmitter to bereadily taken apart and put together without requiring any attention tobe paid to the connection with the circuit-wires.

The vibrations produced by speaking into the mouthpiece are delivered bythe branch tubes against the outer sides of both diaphragms, and thelatter simultaneously compress the granular electrode from oppositesides, thereby increasing the force of the undulations in the currentwhich transmits the speech to the receiving instrument in which thespeech is reproduced.

In the modified construction of my invention represented in Fig. at apair of transmittin g devices similar to that shown in Figs. 1 and 2 areemployed and mounted as follows: I represents a mouthpiece provided withtwo outer branch tubes jj and an intermediate tube j. k 7.; are twoouter supporting-disks which are secured to the open rear ends of theouter tubes. L L represent two inner supporting-disks arranged on theinner sides of the outer disks and secured to opposite sides of the openrear end of the intermediate branch tube. A transmitting device similarin every respect to the one shown in Figs. 1 and 2 is inserted betweeneach outer supporting-disk and the opposing inner supporting-disk. Thevibrations of the speech delivered into the mouthpiece are distributedequally between the intermediate tube which conducts the sound to theinner diaphragms of both transmitting devices and the outer tubeswhereby the sound is conducted to the outer diaphragms of bothtransmitting devices.

I claim as my invention 1. The combination with the mouthpiece providedwith two branch tubes, of two supporting-disks secured to said tubes andseparated from each other so as to form an opensided space between thedisks and a transmitting device arranged in said space, substantially asset forth.

2. The combination with the mouthpiece provided with two branch tubes,of two supporting-disks secured to the open ends of the tubes andseparated from each other so as to form an open-sided space between thedisks, a supporting frame or ring arranged between said disks andprovided on opposite sides with annular seats, two diaphragms bearingwith their marginal portions against said seats, packing-rings fittingagainst the marginal portions of the diaphragms and an electrodearranged between said diaphragms, substantially as set forth.

3. The combination with the mouthpiece provided with two branch tubes,of two supporting-disks secured to the open ends of the branch tubes andseparated so as to form an open-sided space between the disks, atransmitting device arranged between said disks and provided with twodiaphragms arranged adjacent to said disks and contact-springs securedto said disks and bearing against said diaphragms, substantially as setforth.

4. The combination with the mouthpiece provided with two branch tubes,of two parallel supporting-disks secured to the open ends of the branchtubes and provided on their inner sides with pockets, of a transmittingdevice arranged between said disks and provided with two diaphragms andcontactsprings secured to the bottom of the pockets and bearing againstthe diaphragms, substantially as set forth.

lVitness my hand this 10th day of November, 1895.

lVALTER L. \VILHELBL lVitnesses:

THEO. L. PoPP, E. R. DEAN.

